WO 2006/079132 A1 already proposed a method for reducing metal-oxide-containing slags or glasses and/or degassing mineral melts and the respective device for carrying out that method, in which the molten slags were charged onto an inductively heated coke bed, wherein the charge was supplied to a substantially closed shaft reactor and the coke bed was inductively heated to temperatures that were to safeguard that a melt would form as far as to the tap end or the melting temperature would be maintained. In that known device, oxygen was injected in different axial sections of the furnace and the shaft furnace was inductively heated in different sections at different frequencies and with different energies. In that known device, the redox potential of the bed or column could be controlled by the blowing-in of gases, wherein the known device comprised axially consecutive sections equipped with separate temperature measuring means and/or electric power input measuring means in order to thereby ensure an appropriate control of the temperature in the individual sections. It was essential for the known device that the electric energy was directly introduced into the coke bed, wherein the walls or housing themselves were made of refractory material, which was not heated when applying electric energy and, hence, configured in an insulating manner over that temperature range which was to be expected in the region of the housing walls. The housing itself was designed to be cooled just as the induction bodies or induction coils, since the induction heat was actually secured by the accordingly conductive coke particles.
The invention aims to further develop a method and device of the initially defined kind to the effect that any charging materials like zinc-coated scrap, shredder light fraction, rolling mill scales loaded with organics, zinc-containing dusts, sewage sludge combustions ashes possibly containing P2O5, Fe2O3, CaO, Al2O3, ZnO etc., and electric scrap can be processed in a simple manner and noxious substances can be drawn off nearly quantitatively without forming internal circulations. The invention, furthermore, serves to perform the method in a manner that the closed configuration of a cupola furnace can be obviated and a simple shaft having an open, cold charging end can be employed without having to fear the escape of noxious substances there. By the known use of insulating materials for the refractory lining and/or shell of the shaft, it is to be ensured again that the electric energy will merely take effect in the region of the coke bed.